


Not By The Soul

by sailorstarsun



Category: Free!
Genre: Alternate Universe - Future Fish, Alternate Universe - Soulmates, M/M, kind of Sousuke/Aiichiro, kind of Sousuke/Rin, mention of Haruka/Makoto
Language: English
Status: Completed
Published: 2014-10-13
Updated: 2014-11-03
Packaged: 2018-02-21 01:12:17
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,650
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2449817
Author URL: https://archiveofourown.org/users/sailorstarsun/pseuds/sailorstarsun
Summary: <blockquote class="userstuff">
              <p>On Sousuke's 25th birthday he would find out who his soulmate was.  But he already knew it would be Rin.  It had to be.</p><p>It just had to be.</p>
            </blockquote>





	1. Chapter 1

It was the buzzing of his phone from its place next to his pillow, signaling an incoming text message, which woke him up, more than the excitement of the day. Though he _was_ excited about the day – incredibly so. It was a wonder he had gotten any sleep at all.

The message was from Rin, as expected. It simply read 'Has it happened yet?' but it made Sousuke smile. According to the clock at the top of his phone's display, he had been 25 years old for a grand total of eight hours, and already Rin was asking, as if it meant as much to him as it did to Sousuke himself.

It likely did.

It was Sousuke Yamazaki's 25th birthday, and the day he would find out the name of his soulmate. As if he didn't already know.

The name hadn't been imprinted on his body yet. He didn't know when or where it would appear, but he expected it to come with a little bit of pain or discomfort. Gou said it felt an awful lot like a girl's time-of-the-month cramps when it happened, so Sousuke wasn't worried about it hurting like some people claimed. He was a big guy – a staggering 185 centimeters and built nicely from frequent swimming sessions and rigorous training with the police force he and Rin worked for. He wasn't worried about some cramps.

Gou, Rin's sister, was the first of their circle of friends to reach her coming of-age, despite being the youngest. Since girls came of-age at 21 instead of 25, she rushed past all of them to her sexual maturity, much to Rin's chagrin. While he claimed he understood that girls simply matured faster and tended towards older guys, making the biology of soulmates sound, it didn't keep Rin from going into protective older-brother mode once she became a sexually-aware young woman. Any guy who dared so much as glance in Gou's direction got a fierce red glare and a showing of sharp, pointed teeth. Rin's only consolation was that none of them, including Gou herself, had any idea who 'Seijuro' was. When she pulled up her shirt to show everyone the blazing red name printed on the right side of her waist, nobody had a clue who it could be. It frustrated Gou, because soulmates' lives were supposed to be connected somehow. There should have been some link bringing them together, yet not one person Gou asked about the name could provide even a scrap of information. It was unfortunate the brand didn't come with a last name. All she could do at the time was wait and pray it was a simple case of her not having met her mate yet. If it turned out he was younger than her, she could be waiting for years.

It was worse for her while she was in heat. Considerably more stressful on Rin, too. Gou's heat hit a few days after her 21st birthday, and the regular flashes of lust and desire were painful to her. She was lucky one of her closest girl friends from college – Hana-something-or-other – was in heat as well. The two girls helped each other out, and even if it was less satisfying than if they could be with their own soulmates, it got them through a trying time.

Whoever Seijuro was, he missed an important part of Gou's life. Her heat tapered off after a year, like normal, and her sexual need was at its stable, average rate. It was one of the unfortunate possibilities, but they supposed it could have been worse. According to Hazuki, in the ancient past, people didn't even have soulmates. Everyone just chose mates on their own, usually based on physical appearance or wealth or in some other haphazard way that created bonds that didn't last and broken homes. Children were left missing a parent at best, or used as a weapon between former lovers. At least evolution had stepped in and fixed that, though there were things about soulmates that biologists still couldn't explain. Nobody understood how the body's genetics knew what name to brand, or how it knew when to not bother branding a name at all. Hypothesis ranged from magic to aliens to the individuals' atoms meeting millennia before making up the people; nobody really knew.

Neither Rin and Gou's father nor mother had a soulmate. No names ever appeared on their skin, meaning they were destined to die at a young age. Human bodies didn't give a brand to someone who wouldn't live long enough to ever meet their soulmate. But the Matsuokas were determined to have children, despite their lack of the sexual interest that would have come with a brand, and found a way. Rin made it sound super romantic; Sousuke thought it was selfish of them to have children knowing they would end up orphans, but was grateful for the dear friends it gave him. And he was probably just as relieved as Rin was when the name appeared on Gou's body. Unlike their parents, she would live a long, full life.

Sousuke punched in a quick reply to Rin. 'It's only eight. No, it hasn't happened yet.' Still, he couldn't keep a grin off his face.

The next message came almost immediately. 'I'm hopping in the shower, then I'll be right over.'

Sousuke dropped the phone next to his pillow and sat up. Both he and Rin had taken the day off of work to celebrate Sousuke's birthday and coming of-age. Though they were waiting on some leads that could crack the Mikoshiba investigation, they could afford a day off. Especially for such an important day.

He knew it would be Rin. It had to be. He and Rin had been so drawn to each other their entire lives. They had become fast friends in elementary school, and were rarely separated. The only significant time they spent apart was when Rin went on a study-abroad program in Australia, but once he came back they were together again and it was like he had never left. Sousuke honestly couldn't imagine anyone else as his soulmate.

He continued to smile as he slipped from his bed and padded toward the kitchen, trying to keep his steps light so that his neighbor in the apartment below his didn't make another complaint about him stomping around. He prepared some rice, enough for two, and set up a pot of coffee to brew. There was some leftover miso soup in the fridge; it would be a small breakfast, but they would be having a large meal later on.

His smile persisted as he grabbed a towel and headed off to take a shower himself. Though the morning was free for he and Rin to be alone together for a bit, in the afternoon they would meet up with their friends for a small celebratory dinner. He hoped the brand came before then, and somewhere decent, because Sousuke could already hear Hazuki's voice asking "Has it happened yet? How about now?" on repeat, just like he had done to Nanase via text, every half hour, two-and-a-half months ago. Sousuke considered himself lucky that Hazuki didn't have his phone number or his cell's mail address.

Haruka Nanase was the second of their group to come of-age, and the first guy to do so. Everyone had been positive his soulmate would be his best friend since childhood, Makoto Tachibana, so it wasn't at all surprising when the name appeared on Nanase's left collarbone in a brilliant shade of green. Of course, technically there was a chance it was a different Makoto, and they wouldn't know for sure until Tachibana's birthday rolled around the following month, but that was extremely unlikely. Really, the only shocking thing about Nanase's coming was that his heat hit within a few hours of the brand showing. His dinner was quickly cancelled and word was that Tachibana spent that day, and most of his time in the months since then, 'attending to' Nanase's needs.

Now it was Sousuke's turn to have his brand appear, and he also had a friend who meant everything to him. He knew it would be Rin.

The shower was warm; it felt good. Sousuke was rinsing shampoo out of his hair when the first twinge came, starting in his left hip. It was so slight at first, he almost wrote it off as a random body creak, until it began to grow in intensity, spreading through his legs and toes, up to his chest and arms. His whole body tensed and clenched, his muscles squeezing and twisting. It hurt, a lot. His insides felt like they were being ripped apart as he gritted his teeth; his skin felt like it was on fire. Sousuke fell to his knees, gripping the side of the tub in strong fingers as painful groans escaped the back of his throat. It was, admittedly, a lot worse than he ever imagined it would be.

Minutes passed and the pain began to subside. Sousuke's fingers loosened their grasp on the tub and he took a few shaky breaths before climbing to his feet. Then he immediately rushed from the shower, heading for the full-length mirror in his bedroom. He had left the shower running in his haste and dripped water all over the floor, but all he could think about was seeing the name. He wanted to see his soulmate's name branded into his skin.

His eyes roamed carefully over his naked reflection's body, looking for the lettering that would surely be red. He looked for 'Rin'. There was nothing in any obvious place, nothing on his chest or his abdomen or his dick. There was nothing on his legs or his feet or on either side of his neck. His arms and hands were bare as well.

Turning around, Sousuke checked his shoulders and back, finding nothing until he got to his left hip. And his eyes widened as his heart broke.

It was a light blue, and it read 'Aiichirou'.

Sousuke could only stare for a moment, almost refusing to believe what he saw. It seemed to mock him, this stranger's name, as if telling him he wasn't good enough for Rin. Rin wasn't his soulmate; Rin would belong to someone else. And after he had stared long enough, he glared. He hated the name; he didn't feel any affection for his supposed soulmate.

The doorbell rang, snapping Sousuke to attention. Rin was here. Rin was here, and he would see that they weren't soulmates and he would be hurt. He would be angry. He would cry, and his tears would shatter Sousuke's heart to unrepairable pieces.

With a start, Sousuke moved quickly. He went back to the shower and turned the spray off, then grabbed his towel and wiped his body mostly dry as he went back to the bedroom. The doorbell chimed again and again, becoming incessant as he hurriedly dug out some underwear and a pair of shorts and pulled them on. Making sure the brand was hidden, thankful that, if nothing else, it was low enough to be covered casually, he went to the door and yanked it open.

Rin stood there, looking faintly annoyed. He gave a scowl, asking "What took you so long?" but even the grumpy expression didn't diminish how _pretty_ Rin was, with his dark red hair dancing around his face as an early autumn wind blew. And now, with his fully matured eyes, Sousuke could see that Rin was nothing short of sexy.

Sousuke just stared for a moment, his mouth automatically replying "I was in the shower."

Then Rin broke into a grin, his excitement shining through. "So, did it happen yet?"

Sousuke's heart contracted in his chest, and he honestly thought it might be better to die than to be the one to make Rin lose that smile. For a moment, his voice caught in his throat and he couldn't respond, until his arms shot out, pulling Rin to him. He held Rin to his chest tightly, pressing his face into still-damp red hair, and after a length of time he finally whispered "It's you."

Rin pulled back enough to look up into Sousuke's face. "Really!?" he asked, excited.

"Yeah." It was going to hurt so much later on; when Rin's birthday came he would see the names didn't match, and everything would end. But for now, just for now, if he could have that smile a little bit longer, it would be worth it. "Of course it's you."

"That's great!" He laughed with a joy that broke Sousuke a little bit more. "Let me see it."

Sousuke tensed and his arms dropped from where they had been resting around Rin. He turned and walked further into the apartment, heading for the bedroom. "You can't," he said in a controlled voice.

Rin followed, not needing to be invited in. "Why not?"

"It's in a really embarrassing place," Sousuke answered as he grabbed a t-shirt from his closet and pulled it over his head.

"Oh, come on," Rin persisted. "We're best friends. We're _soulmates_. You can show me."

"No."

"What, is it in the crack of your ass or something?"

Sousuke gave him a _look_ as he pulled a loose overshirt from the closet and slipped it on, then averted his eyes, putting on a nervous face. That actually was the most embarrassing place he could think of.

"Oh my god, really?" Rin asked, falling for the ploy. "You poor bastard."

"Yeah," Sousuke replied as he brushed past Rin, heading for the kitchen to dish up the breakfast he had prepared. "So, sorry, but I'm not ready to show it off just yet." He switched off the rice cooker as he went by, and heard Rin behind him as he reached into a cupboard for two plates and a pair of soup bowls.

"Don't worry about it," Rin said, and Sousuke turned to see him leaning against the door frame. He had given up way too easily; it was disturbing. Then with a grin he added "I'll just wait until your heat hits."

Sousuke's eyes widened as images came crystal clear into his mind. His heat would come, Rin would offer to help give him relief and Sousuke's lust-addled mind would be unable to refuse. Rin would see the brand, see the truth, and be hurt and angry. Rin would cry, and it would be all Sousuke's fault.

Unless he could fight it. He _would_ fight it. He had to. Even if the heat left him clawing at the walls, he would fight it, tell everyone he was fine, and take care of it himself.

Looking across the small kitchen, Sousuke let his teal eyes meet Rin's deep red. He would say it now while he still could.

"I care for you so much."


	2. Chapter 2

The birthday-slash-coming-of-age dinner started off fun. It was at an izakaya with a set meal that had plenty of meat, which made Rin happy, and a side order of mackerel, to appease Nanase. And of course, all-you-can-drink alcohol. Everyone congratulated Sousuke and Rin both, and then the "Cheers!" and clinking of glasses long passes, most of the food gone, when Hazuki started on about Sousuke's brand.

"It's Rin-chan, right?" he said far too innocently to be genuine. "So it's no secret. Let's see it!"

"No, it's private," Sousuke answered blandly, and then took another drink of his beer.

"But we're friends! You can show your friends! We've seen Haru-chan's."

Tachibana chuckled from where he sat on the other side of the low table next to Nanase, whose eyes simply glanced to the side. "Haru's is in a decent place," Tachibana said with his usual smile. "You shouldn't bother Yamazaki-kun if his is somewhere he's uncomfortable showing."

"Like his ass crack," Rin added with a grin.

Sousuke gruffed a growl, but didn't get a chance to respond before Hazuki laughed loudly. "Really!? But that's okay! We're all guys here, so you can show us."

"We are _not_ all guys here," Gou said with a scowl.

"Gou-chan can close her eyes," was Hazuki's answer, as if it were that simple and obvious.

Sousuke had a _look_ that could make the hardest of criminals confess, and he gave it to Hazuki full-force. "Nobody is seeing any part of me."

It had little effect. "But, Sou-chan-"

"Don't call me that."

"But, Sousuke," Rin cut in, throwing an arm around Sousuke's shoulders. His eyes twinkled mischievously. "What would happen if, say..." Then he twisted Sousuke's shoulders while pushing him down, causing Sousuke to hit the floor chest first. He climbed onto Sousuke's back, sitting on him and holding him down. He finished by saying "You were to fall over?"

"Get off," Sousuke growled.

To his horror, Hazuki joined in, tugging lightly on his shorts. "And your pants were to accidentally come down?"

Sousuke flailed, but was unable to buck Rin off of him. " _Stop_."

"It would totally be an accident!" Hazuki said as he continued to tug, deftly dodging Sousuke's kicking legs until he was finally able to sit on them, pinning Sousuke completely. Hazuki may have been short, but he was fit – as a pilot in the space program and hopeful for the next flight, he had to be.

There was a rare warning tone in Tachibana's voice as he simply said " _Nagisa_."

"It's all hypothetical!" His pulling brought Sousuke's shorts down a centimeter further.

Sousuke gritted his teeth, seething. They would see. A little bit further and _Rin_ would see and all Sousuke could do was uselessly fight and growl at the floor, preparing himself for the inevitable.

But then all movement stopped. Only a breath passed before the weight lifted from his back and legs, freeing him, and Sousuke immediately jumped to his feet and turned with his deepest glare. Rin and Hazuki both laughed loudly like the brats they were.

"Come on, Sousuke," Rin said, still grinning. "You know we wouldn't really do anything."

"Sou-chan is _sou_ grumpy, and on his birthday too."

Sousuke fumed. He wanted to shout, but for the sake of everyone else there, he didn't, and it wouldn't have done any good anyway. They had stopped; he would have to be satisfied with that. He was about to sit down again, but before he could move Rin smiled, "Calm down," and gave another playful tug at Sousuke's shorts.

It was all that was needed to bring them far enough down. Already riding low from Hazuki's playing, the final pull dragged Sousuke's shorts and trunks both low enough to reveal the brand on his hip. Though Sousuke quickly grabbed at the waistband and yanked his clothes back up, it was already too late. Rin's eyes were wide, his red irises seeming to have shrunk in horror. There was no point in even hoping he hadn't seen.

"Rin..." Sousuke started. He waited for the tears to start.

Instead, Rin's brows drew down and his eyes narrowed. "Who is he?"

"I don't know," Sousuke answered.

"The hell you don't! Who is he!?"

"I said I don't know!"

The entire izakaya fell silent for a beat, and Sousuke was aware of the eyes that glanced into their booth, though he didn't move a muscle. He waited to see what Rin would do, letting him take the lead, as usual. When the izakaya's noise returned in whispers and chatter, Rin stood. "Let's go outside," he said, shoving his hands into his pockets as he walked out without looking at anyone.

Sousuke met him on the far side of the izakaya's parking lot. It wasn't totally secluded, but at the moment it was far enough away from prying ears. Rin stood with his back to Sousuke, and didn't turn or speak even as Sousuke came up behind him. After a moment, Sousuke spoke first, saying "I'm sorry."

"Why did you lie to me?"

"I knew you would be upset."

"I would have found out eventually."

The explanation of how he had just wanted a little more time felt dumb all of a sudden, so Sousuke simply replied "I know." Then he heard Rin sniffle, crying after all; it was something of a comfort. "I wasn't lying when I said I care for you," he said softly.

"But you'll care for him more."

"I don't even know him. What if I never meet him?" Sousuke stepped forward, closing the space between them, and put his hands on Rin's shoulders. "What if I never look?"

"Sousuke..." Finally Rin turned around so they could face each other. His eyes were wet, but he seemed to be calming down. "Don't-"

"We could ignore all this soulmate nonsense," Sousuke cut in. "I know who I'm meant to be with."

Rin was still for a moment, and then a smile touched his face as his head lowered. "No," he said with a single shake of his head. "You'll meet him someday, and you'll love him so much. I wouldn't want to deny you that."

"Rin..." But Sousuke knew he was right. Even if they tried to ignore the names that branded onto their bodies, the longing would be there. Even if he spent forever with Rin, he would always be subconsciously yearning for 'Aiichirou'. It was simply a matter of biology. So then he sighed, conceding. "I won't care for him more," he said at last. "Only differently."

Rin snorted, but then finally smiled softly, and Sousuke flooded with relief. "I thought I was the romantic one," Rin teased lightly.

"I can be romantic."

"You haven't got a romantic bone in your body," Rin replied as he began walking back towards the izakaya. "I almost feel sorry for your mate."

Sousuke caught up easily, falling in beside Rin. "You thought what I said just now was romantic."

"A fluke."

And they laughed as they returned to their friends, together.

 

 

 

-End-

**Author's Note:**

> Thanks for reading!  
> It's probably been, like, a decade since I've written fanfiction, so I'm probably very rusty. I apologize if this isn't very good.
> 
> I've adored all of the soulmates AUs I've read on here so much! So I wanted to try one of my own. I know the idea has been done and done, but I hope this is still at least a little bit interesting for you.
> 
> Thanks!


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